In flight simulator visual systems, a wide (especially horizontal) operator field-of-view is desirous for realism. Typically in present day systems, computers provide the image generation. In order to cost effectively utilize the computer image generator to its compacity for maximum realism, area-ofinterest systems have been developed. In such systems, only an instantaneous field-of-view is presented to the operator, eliminating image generation by the computer in those areas not instantly viewable by the operator. One such area-of-interest system is shown in U.S. Pat. No. 4,103,435 issued Aug. 1, 1978 to Herndon. The location of the displayed image is aligned with the operator's instantaneous field of view through sensors mounted on a helmet worn by the operator so that regardless what direction the operator is facing relative to the display screen, an image sufficient to encompass the operator's instantaneous field-of-view is projected.
Although the helmet-slaved, area-of-interest system does allow cost effective computer utilization for image generation, such a system creates problems with respect to image projection and display for a wide angle field-of-view. In order to ensure a resultant display image of sufficient intensity and resolution over the total wide field of view (e.g. 235.degree. azimuth), multiple light projectors are necessary. The use of two or more light projectors individually moveable in response to operator induced helmet movement creates critical image abutment and alignment problems that must be resolved for display realism. Another problem associated with multiple light projectors is distortion which results from physical location of each projector exit pupil relative to the display screen (typically a concave spherical dome). Ideally, each projector exit pupil would be placed at the radius of curvature of the dome, which is not physically possible. Thus it is necessary to correct for distortion of each projector image, thereby increasing the overall complexity of the projection system.
In an attempt to reduce the projection problems stated above, Spooner in U.S. Pat. No. 4,048,653 utilized a helmet-mounted binocular viewer, while Harvey in U.S. Pat. No. 4,348,186 employs a helmet-mounted projector. Because neither of these types of devices are present in the actual pilot/cockpit environment, realism is sacrificed.
The invention described and claimed herein provides a helmet-slaved, area-of-interest visual system having a wide total field of view (280.degree. azimuth; .+-.75.degree. elevation) that gives maximum utilization of computer image capability in conjunction with two or more light sources for enhanced intensity and resolution in the displayed image while eliminating image abutment and distortion problems.